As for the actual requirements we want an update of the old logo rather than something radically new. We have tons of stuff bearing the old logo that we cannot afford to replace. So the new logo needs to have some resemblance to the old one.
It is absolutely mandatory to keep the frog. Feel free to make any changes to the appearance of the frog, except it's color. And please note that we prefer an abstract look over a cartoonish one.
The biggest problem with the current font that people have is the fact that it is a serif font. The new logo should make use of a sans serif font or a custom illustration.
If you use an existing font, make sure that we can use it free of charge. It would be even better if the font were readily available in linux distributions such as Ubuntu, although that is not a must-have.
Feel free to make the new logo as fancy for web and print as you deem fit, but keep in mind that we need to be able to print a monochrome version on t-shirts etc. We might accept something, that needs two colors to look good on a t-shirt, but we would rather not because that makes printing more expensive.
The final result should be a vector graphic file in the SVG-format. We also want the file in the native format of whatever program you used to create it and an EPS version.
And thanks for helping to make FrOSCon 5 rock!